Embodiments of the invention relate generally to synthetic jet actuators, and more specifically to systems and methods for controlling operation of synthetic jet actuators in order to operate the synthetic jet actuator at an optimal operating point with respect to acoustic operating noise, efficiency, operating temperature, and maximizing longevity of the actuator.
Synthetic jet actuators are a widely-used technology that generates a synthetic jet of fluid to influence the flow of that fluid over a surface. A typical synthetic jet actuator comprises a housing defining an internal chamber. An orifice is present in a wall of the housing. The actuator further includes a mechanism in or about the housing for periodically changing the volume within the internal chamber so that a series of fluid vortices are generated and projected in an external environment out from the orifice of the housing. One example of a volume changing mechanism is a flexible diaphragm that forms a wall of the housing, with the flexible diaphragm being actuated by a piezoelectric actuator or other appropriate means. In a dual cool jet (DCJ) construction, two piezoelectric actuators (or other suitable actuators) cause deflection of opposing flexible diaphragm walls of the housing in order to change the volume within the internal chamber of the housing.
Typically, a control system is used to create time-harmonic motion of the volume changing mechanism. As the mechanism decreases the chamber volume, fluid is ejected from the chamber through the orifice. As the fluid passes through the orifice, sharp edges of the orifice separate the flow to create vortex sheets that roll up into vortices. These vortices move away from the edges of the orifice under their own self-induced velocity. As the mechanism increases the chamber volume, ambient fluid is drawn into the chamber from large distances from the orifice. Since the vortices have already moved away from the edges of the orifice, they are not affected by the ambient fluid entering into the chamber. As the vortices travel away from the orifice, they synthesize a jet of fluid, i.e., a “synthetic jet.”
While synthetic jet actuators are generally recognized as being durable cooling devices, it is recognized that they can be subjected to a range of environment conditions during use and that this can lead to degradation and eventual failure of the synthetic jet actuators. If possible, it is highly desirable to prevent such failures from occurring, as the replacement of synthetic jet actuators can be time consuming and, in some cases, can also necessitate shutdown of the system or components to which the synthetic jet actuators are designed to provide cooling to. It is recognized that altering operation of a synthetic jet actuator (e.g., reducing input power, operating voltage, operating frequency, etc.) can help to prolong the life thereof; however, it is also recognized that certain operational/system requirements may be present that would restrict how the operation of the synthetic jet actuator can be altered—including temperature requirements and acoustic level requirements, for example.
Accordingly, it would be desirable to provide a system and method for monitoring the operating conditions of a synthetic jet actuator in order to identify degradation and a potential failure of the synthetic jet actuator, so as to enable adjustment of the operating parameters of the synthetic jet actuator to counteract degradation and prevent premature failure. It would also be desirable for such a system and method to—in adjusting the operating parameters of the synthetic jet actuator to counteract degradation and prevent premature failure—determine a manner in which to implement such adjustments that optimizes performance of the synthetic jet actuator with respect to meeting temperature requirements and acoustic level requirements.